embed_subtitles

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure. It openly explains that subtitles are soft and selectable, not burned into frames, and lists supported output formats. It does not cover output file creation or error scenarios, but the core behavior is transparently described.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is exceptionally concise: one sentence for the core action with a parenthetical clarifying the soft-subtitle nature, and a second sentence listing supported formats. Every word adds value, and no information is repeated unnecessarily.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description, paired with the rich schema, covers the tool's purpose and key constraints. However, because there is no output schema and no annotations, the description omits the return value and whether a new file is created or the input is modified. These gaps reduce completeness for an agent that needs to predict tool behavior.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already covers all 4 parameters with clear descriptions (100% coverage), so the baseline is 3. The tool description adds no meaningful parameter semantics; it merely repeats the format support already present in the output_format parameter description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the tool's function: 'Embed a subtitle file as a soft subtitle track inside a video container'. The verb 'Embed' and the resource 'subtitle file' are specific, and the parenthetical 'selectable but not burned into the video frames' distinguishes it from burned-subtitle tools like burn_subtitles.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context on when to use the tool (when selectable soft subtitles are needed) and contrasts it with burned-in subtitles, effectively communicating the use case. However, it does not explicitly name an alternative tool or provide 'when not to use' guidance, which would be needed for a perfect score.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.